Silodosin is an indoline compound, chemically known as 1-(3-Hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2-trifluoro-ethoxy)phenoxy]ethyl}amino)propyl]-2,3-dihydro-1H-indole-7-carboxamide and represented by Formula (I).

Silodosin was disclosed in U.S. Pat. No. 5,387,603 as therapeutic agents for the treatment of dysuria, urinary disturbance associated with benign prostatic hyperplasia.
Few processes for the synthesis of Silodosin have been described in the literature.
The Synthesis of Silodosin is relatively complex, involves multiple steps in the preparation of optically active amine compound of Formula (X) and there by condensation with phenoxyethane compound of Formula (Y) followed by deprotection and conversion of cyano group to carbamoyl group.

EP1806340 patent application relates to a process for the preparation of silodosin comprising mixing 3-{7-cyano-5-[(2R)-2-({2-[2-(2,2,2-trifluoroethoxy)phenoxy]-ethyl}amino)propyl]-2,3-dihydro-1H-indol-1-yl}propyl benzoate of Formula (1) with oxalic acid to produce corresponding monooxalate salt compound. Hydrolyzing the obtained monooxalate compound to yield 1-(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2-trifluoroethoxy)phenoxy]-ethyl}amino)propyl]-2,3-dihydro-1H-indole-7-carbonitrile represented by the Formula (2), further hydrolyzing the compound of Formula (2) to yield Silodosin.

There are several disadvantages involved in the processes disclosed in prior art references. Mainly, the prior art processes involved alkylation of compound (X) by compound (Y), this reaction often leads to over alkylation and produces undesired compounds accordingly yields of the desired compound are very low. The present inventors have surprisingly found that employing intermediates of the present invention in the process for the preparation of Silodosin, overcomes the drawbacks of the prior art and may be prepared and subsequently converted to Silodosin in high yield and purity.